The present disclosure relates to an edge dam of a twin roll type strip caster in close contact with both side surfaces of a casting roll used in a twin roll type strip caster to prevent leakage of molten steel.
A twin roll type caster according to the related art is an apparatus for rotating a pair of casting rolls in a direction in which the pair of casting rolls face each other, and pouring molten steel into a space between the pair of casting rolls to continuously cast strips.
With reference to FIG. 1, in a twin roll type strip caster, molten steel is supplied to the space between a pair of casting rolls R and R′ facing each other and disposed to be parallel to each other, and a pair of edge dams E and E′ formed of a flat refractory material in a trapezoidal form on both ends of the casting rolls R and R′ are installed to confine molten steel between casting rolls R and R′ and to form a slab to have a uniform width.
A level of performance of the edge dams E and E′ is an important factor in determining casting stability, maximum casting capacity, as well as edge quality of a strip, and the edge dams E and E′ are provided to have various sizes, shapes, material compositions, and the like, of a refractory material according to a diameter of a casting roll, casting capacity, an operating method, a grade of steel, and the like.
In addition, to allow the edge dams E and E′ to stably seal molten steel during casting, the edge dams E and E′ are required to be pressed by end surfaces of the casting rolls R and R′. To this end, to press the edge dams E and E′ to end surfaces of the casting rolls R and R′ with a predetermined degree of force to be in close contact therewith during casting, devices for fixing and driving an edge dam are provided on a side surface or a rear surface of the edge dams E and E′.
A fixing device is a device for mounting the edge dams E and E′ to be firmly fixed. In addition, on a rear surface of the fixing device, driving devices for adjusting positions of the edge dams E and E′ towards the front and the rear, the top and the bottom, and the left and the right are provided.
However, as the edge dams E and E′ are pressed by end surfaces of the casting rolls R and R′, a sealing member 1 (see FIG. 2) is continuously worn. When the sealing member 1 is worn by more than a certain amount, molten steel may be leaked. Thus, there may be limitations on performing further casting.
In detail, as the sealing member 1 provided for the edge dams E and E′ is continuously worn, the casting rolls R and R′ may dig into a surface of the sealing member further and further to be embedded therein. In addition, a width of a molten steel solidified shell formed on the surface of the casting rolls R and R′ and a width of a slab are reduced by an amount equal to a depth to which the casting rolls R and R′ are embedded.
In addition, due to continuous friction between a solidified shell formed on a surface of the casting rolls R and R′ and a specific portion of the sealing member 1, a groove is generated in the sealing member 1. When the groove is worn beyond a certain depth, problems in which a quality of an edge portion of a slab is poor, molten steel leaks, and the like, may occur.
As disclosed in Japanese Utility Model Publication No. 1992-043447 and Korean Patent Application No. 2003-0095779, according to the related art, a device for raising the edge dam E is provided, and a method for raising the edge dams E and E′ in proportion to an amount by which the sealing member 1 is worn is suggested.
However, in a structure such as that described above, in comparison to an area in which a sealing member of an edge dam is initially in contact with a casting roll, when the edge dam is raised, an area contacting a casting roll is reduced. Thus, a degree of wear of the sealing member 1 is increased, a problem in which a service life is sharply reduced may occur.
FIG. 2 is a front view of an edge dam of a twin roll type strip caster according to the related art, while FIG. 3 is a cross-sectional view taken along line I-I′ of FIG. 2. In addition, FIG. 4 is a front view of an initial position and a raised position of an edge dam of a twin roll type strip caster according to the related art, and FIG. 5 is a cross-sectional view taken along line II-II′ of FIG. 4.
With reference to FIGS. 2 to 5, an edge dam E includes a sealing member 1, and the sealing member 1 is in close contact with an end surface of a casting roll R to seal a gap.
The edge dam E is worn while casting is performed, and the edge dam E is continuously pressed and raised.
However, while casting is performed in the edge dam E, a surface in which the sealing member 1 is in contact with the casting roll R is worn, and thus, in comparison to an area in which the sealing member is in contact with the casting roll at a beginning of casting, a contact area is gradually reduced. (In FIG. 4, a deviant crease lined part P illustrates a part in which the sealing member 1 is in contact with the casting roll R).
Meanwhile, both side surfaces of the sealing member 1 of the edge dam E are formed at an incline. A structure described above is a structure for preventing edges of the sealing member 1 from being easily damaged in a case in which the edges thereof form a right angle.
Due to the structure described above, a difference in contact areas of the sealing member 1, in a process in which the edge dam E according to the related art is raised, may be somewhat reduced. However, with such a structure alone, there are limitations on preventing the contact areas of the sealing member 1 from being different, and thus, there are limitations on relieving concentrations of stress and increases in wear.